The radius of the LGB R5 and the Piko R5 are not the same, so 12 pieces of Piko track won't complete your circle.
The diameter of a circle of LGB R5 track is 182.68 inches (a little over 15 feet), while the diameter of a circle of Pko R5 track is 97.83 inches (a little over 8 feet).
Piko's R5 is close to LGB's R3 (94.095 inches).
The diameter of a circle of LGB R5 track is 182.68 inches (a little over 15 feet), while the diameter of a circle of Pko R5 track is 97.83 inches (a little over 8 feet).
Piko's R5 is close to LGB's R3 (94.095 inches).